The Norse creation myth begins with a murder. The Norse gods believe is necessary to kill the giant Ymir, who was always a bit of a hooligan, because he has become increasingly uncontrollable in his old age. His murder symbolizes the suppression of primal appetites that must occur before society can come into being. In other words, people have to put aside their selfish urges in order to cooperate and create something larger than themselves.
Once they get down to creating, a big part of the gods' work is to separate and organize. Water breaks apart from land, races become distinct from one another, day becomes separate from night. The gods create rules for the cosmos, like the cycle of night and day, and the proper location and activities of the different races and animals.
Like in most creation myths, though, the forces of chaos never disappear completely. In the Norse cosmos, they're present in the primal Frost- and Fire-worlds that still exist even after the creation occurs, and in the race of giants who survive to threaten the world that has (literally) been built on their back.